Heat transmission units for use in internal combustion engines are generally known and have been described in a large number of patent applications. Heat transmission units of this type serve both for the cooling of gases, such as e.g. charge air or exhaust gas, and for the cooling of liquids such as e.g. oil.
Not least due to their large variety of possible uses, heat transmission units are known in very diverse configurations. Examples in this regard are, particularly, tubular radiators, plate-type radiators and radiators of the die-cast type.
Especially in the cooling of exhaust gases, an excessive sooting of the channels for exhaust-gas throughflow should be prevented; as a result, the cross section of the channels should not be selected to be too small. In order to provide a reliable heat transition in spite of this restriction, radiators have been developed, particularly of the type produced by die casting, wherein the partition walls between a channel for cooling-fluid throughflow and a channel for throughflow of the fluid to be cooled are provided with ribs extending into the channel for the to-be-cooled fluid. Particularly in case of high temperature gradients, these ribs will considerably improve the heat transition.
A heat exchanger of the above type is known from DE 10 2005 058 204 A1, for instance. The heat exchanger disclosed therein comprises an inner shell and an outer shell, with the cooling fluid flowing between the outer shell and the inner shell while the fluid to be cooled will follow a U-shaped course through the inner shell, i.e. will first flow via the inlet into an inflow portion and from there, via a deflection region and a subsequent return flow portion, to the outlet. From the partition wall between the two channels, ribs extend into the fluid-conducting channel along the whole length of the channel.
Heat exchangers of the above configuration have been found to suffer from the disadvantage that the cooling effect will decrease along with a decreasing temperature gradient. Further, the deflection region of such a U-shaped heat transmission unit will accumulate distinctly more sooting, thus causing an increasing loss of pressure.
Thus, it is an object of the present invention to provide a heat transmission unit wherein, while the pressure loss remains the same or is even smaller, the cooling efficiency is improved in comparison with known configurations, while not requiring additional constructional space for this purpose.